1. Field of the Invention
The present invention relates to a bobbinless coil comprising a conductor wire which is wound into a coil shape and which exposes its inner peripheral surface, and a method of manufacturing the bobbinless coil.
2. Description of the Related Art
A coil used for an electromagnetic actuator or a motor is wound around an insulator which is generally called a bobbin. However, a bobbinless coil without such a bobbin is known from Japanese Patent Application Laid-open No. 10-172823. In this bobbinless coil, a tape having a bonding layer is spirally wound around a conductor wire; the conductor wire is wound into a cylindrical shape to form a coil body; a plurality of spots in a circumferential direction of the coil body are fixed to maintain the shape of the bobbinless coil.
However, the above described bobbinless coil has a problem that the shape of the coil body is likely to be inaccurate because the bobbin which becomes a guide does not exist when winding the conductor wire. Further, because the conductor wire is bonded over the entire length, there is not only a problem of requiring a large amount of tape with a bonding layer, but also a problem of requiring a large number of steps for winding the tape with the bonding layer.